Mutations affecting the operator of recA will be characterized by nucleotide sequencing techniques. Mutations affecting the activity of RecAp will be mapped relative to each other by amino acid sequencing techniques. Mutations affecting recombination by the RecE and RecF pathways will be further characterized and if possible the gene products affected will be identified. Additional mutants blocked in steps in recombination not heretofore affected will be sought. Mutations permitting E.coli to engage in recA independent homologous recombination will be sought. A genetic system for detecting end products recA dependent recombination will continue to be explored.